Position indicator for machine tools



A ril 4, 1939. j w MaCR E 2,153,424

I POSITION INDICATOR FOR MACHINE TOOLS Filed Oct. 7, 1957 InvEm'un WILLIAMLML'RAE 'T ITRNEYS 3 due to variation in the amount of pressure Patented App-4, 1939 UNITED STATES; PATENT OFFICE I POSITION INDICAfiI? I William L. Mach, Syracuse, N. Y m! 0 Dalrae Tools Company, partnership composed of ,Lapham and William L. Macltae Syracuse, N. 1;, a

De Forest Application-October '1, 19av, .seris1 No. 167,796

' 2 Claims. (01. 90- 16) This inventon relates to a position indicator for machine tools.

' In so far as the applicant is aware, machine tool position indicating devices have heretofore 5 comprised either a rotating dial operatively connected with the positioning mechanism for -producing relative movement of the tool and work toward each other and which rotates in predetermined relation to said relative movement of the tool and work,- or a stop element adiustably connected with the positioning mechanism for positively limiting'the relative movement of the tool and work at the desired position oilthe tool with respect to thework.

is When using the dial as a tool positioning indi- I cator, the dial is necessarily limited in diameter owing to the relatively small space available for the dial or to its being impracticable from the stand point of design. This necessitates an ap- 20 preciable amount of movement or the dial for each fraction of an inch of relative movement of the tool and work toward each other in order that the markings or indicia on the dial may be spaced from each other suillciently to enable the 25 same to be quickly and easily observed or read by 'the operator. It therefore follows that the de- Bree of relative movement oi. the tool and work toward each other is necessarily so limited for each revolution of the dial, the dial usually must to rotate from one to two or even more complete revolutions during the said relative movement of the tool and work to bring the'tool from the inoperative position in space-relation to the work to the operative position:with the tool kissing or as merely touching the work; that is to say in initial contact therewith. This necessitates the operator observing the number of complete revolutions of the dial or fraction thereof each time the tool is brought into contact with the work and @o'mentally recording such movement of the dial.

in order for the operator to be able to know the .v position of the zero mark on the dial as the tool begins its operation on the work. This," of

course, requires .work and painstaking on theas. part of the operator which necessarily slows down the operation of the machine and is conducive of mistakes or errors being made in the final position of the tool at the completion oi the work being performed. a

so When using the adjustable stop in conjunction with the positioning mechanism for bringing the .7

tool into operative relation with the work, there is also opportunity for inaccuracy or minute variationspccurring in the positioning of the }fool duced by the operator on'the control lever or the v positioning mechanism, which in turn produces variations in the relative movement oi the work and tool toward each other by taking up more or less slack in the pivotal connections, bearings, 5 and gearin'gs etc. associated with the positioning mechanism; 7

The main object of this invention therefore, is to provide a position indicator for machine tools, which'will' overcome the above mentioned defects 10 found' in the conventionally constructed position indicators.

Another object of the invention is to provide a tool positioning indicator whereby the position of the cutting edge oi. the tool with respect to the vwork may be readily determined without any process of calculation after the indicator has been set for a given piece of work.

A further object of the invention is to provide a positioning indicator oi the class described by which when once set for a particular movement of the tool, the tool may be used indefinitely for that particularpperation without again resetting the indicator or observing the ammmt of relative movement of the, tool and work as the tool is moved from the inoperative position in spaced relation to the work to the operative position where the tool contacts with the work at the beginning of the cutting operation thereof.

A still further object of the invention resides 3 in. producing a position indicator for machine tools which ail'ords the maximum degree of accuracy and speed in positioning of the tool with respect to the work thereby producing a saving of time and labor-and providing for the eliminain accordance with this invention.

,Figure 2 is a horizontal transverse sectional view taken substantially on line 2-2, Figure l. Figure 3 is a detail vertical sectional view of the lower end portion oi. the mounting shown in Figure 1 taken in the plane of the line 3-3, Figure 2.

Figureiis a detail-vertical sectional view taken on line 4-4, Figure 2.

Figure 5 is a detail vertical sectional view taken on line 5-5, Figure 4 andillustratin'g the portion of the position indicator broken away.

In order to illustrate the novel feature-ct this as ing II with a suitable support on the machine with which the mounting is to be used, such as an over-arm, not shown. The housing II is a onepiece elongated member forming a case for a tool spindle ll.

The spindle ll extends longitudinally through the housing II with the upper portion thereof normally extending some distance above the housing. -The spindle may be mounted in suitable bearings, not shown, provided in the upper end po' ion it of the housing II for both rotary and axial movement with respect to the said housing. The lower end. portion of the spindle II is shown in Figure 3, Journaled in suitable bearings l1 and II arranged in axial spaced relation to each other between a tool chuck 2. provided on the lower end of the spindle and a nut 2| screw threaded on said spindle in spaced relationto the chuck. A spacing sleeve 22, is shown mounted on the spindle I! between the bearing members l1 and II, for maintaining the bearing member II in fixed spaced relation to the bearing member II. It will thus be observed that the nut 2i, sleeve 22, and'chuck'" coact to clamp the spindle i5 and bearing members l1 and It to each other, so that the spindle may rotate in the bearing member but is maintained against axial movement with respect to said bearing member.

The bearing members "and I. are mounted in a supporting sleeve or quill 24, which in turn is slidably mounted for longitudinal reciprocative movement ina tubular bearing member 2! mounted in the lower end portion H of the housing Ii. The supporting sleeve" or quill 24 is maintained against rotary movement with respect to the bearing 25 and housing Ii by means of a clamp block or key positioned in an elongated slot 21 formed in the outer peripheral surface of the quill 24, said block being rotatably connected with the inner end of a screw 2! which is screw threaded in the bearing member 25 near the lower end thereof and extends outwardly from said bearing member through a suitable aperture 20 provided in the adjacent portion of the housing II. The outer end of the screw member 20 may, as shown, be provided with a knurled head 2| forming a nnger piece by which the screw may be readily rotated. The object of rotating the screw member 2!, is to bring the clamping block 28 into clampingengagement with the quill 24 for releasably looking the quill against axial movement when it is desired to maintain the tool carried by the spindle I! inpredetermined relation with the work, as for instance, when cutting a slot of required depth across the facengfia piece of,work with a milling tool.

The quill 24 is moved axially to bring the tool carried by the spindle ll into and out of engagement with the work by means of a worm nut II, which is rotatably mounted in the housing II between the upper end of the bearing 25 and a thrust-bearing I2, bearing 22 being mounted in the housing II, in inward spaced relation to the bearing 25. The nut II is provided with internal screw threads which are in engagement with a lead-screw 33 formed in the outer peripheral surface of the quill 24 at the inner end portion thereof. A worm gear 34 mounted upon or made integral with a shaft 35, is in meshing engagement with suitable worm gear teeth II, provided on the outer peripheral surface of the nut Ii for producing rotation of said nut. The shaft ll in this instance extends through the housing II at one side of the bearing member adjacent the inner end thereof and is rotatably mounted in suitable bearings 28, mounted in said housing at opposite ends of the worm 24, as shown in Figure 2. Thrust bearings as may, as shown, be mounted on the shaft 35 between the ends of the worm I4 and the adjacent bearings ll.

The shaft 38 has both ends thereof extended beyond the adjacent portion of the housing ll for receiving the hand wheel 4| by which the shaft and gear 34 may be manually rotated. The hand wheel n is preferably releasably secured to the shaft 35 so that it may be readily shifted from one end of the shaft to the other to position the wheel most advantageously for rotating the shaft 35. It will now be observed that rotation of the shaft I in one direction will rotate the nut II for producing axial movement of the quill 24 and the spindle carried thereby, in a corresponding direction while reverse rotation of shaft 25 will produce movement of the quill and spindle in the opposite direction.

The axial movement of the quill and spindle is for the purpose of moving the-tool carried by the spindle into and out of operative engagement with a piece of work supported in co-operative relation therewith, and any suitable power means may be connected with the spindle ll for rotating the same and the tool carried thereby. For this purpose, I have shown a multiple speed pulley 42 mounted in the housing II, at the inner end of the quill 24. The pulley 42 is Journaled in suitable bearings, one of which is shown at 48, Figure 3, mounted in the housing ll adjacent the ends of the pulley. Suitable means, such as an electrical motor, not shown, may be connected with the pulley 42 by a suitable belt, also not shown, for driving said pulley. The pulley 42 is splined to the spindle ii by a key, whereby the spindle may be caused to rotate with pulley and at the same time said spindle is free to move axially through the pulley during the adiustment of the spindle for bringing the tool into and out of operative engagement with the work.

The device thus far described is of conventional structure, and the means for registering the axial movement of the spindle II whereby the position of the tool with respect to the work to be engaged thereby may be determined and which constitutes the novel features of the invention will now be described.

This position indicating means comprises a mechanical counter 48 which is shown mounted on the housing I I by screws 41 in close proximity to and in substantially parallel relation with the worm shaft ID. This counter is of the multiple register wheel type having mechanical connections (not shown and which may be of any suitable well known construction) between the reslster wheels, as 4|, for periodically transmitting motion from a wheel of one denomination to an adjacent wheel of another denomination and a rotatable drive shaft '2 operatively connected with one of said shaft register wheels. This counter as indicated more particularly in Figure 5, is provided with five register wheels 40 which may be observed through a window 8| provided in a casing ii for the wheels. The rotatable drive shaft I2 is journaled in one end of the case Ii and mart is peratively connected by suitable mecha not believed necessary to illustrate or further describe, with the register wheel 49 adjacent said end for rotating said wheel in either direction.

The counter shown is known as a Direct Drive Counter which counts ten units, which in this inv stance represents ten one-thousandths of an inch,

. gear teeth I. and to for each revolution of the shaft 51. The opposite end of the case 5| is provided with a reset shaft 54, which has secured to the outer end thereof a wing knob 55. The other or inner end of shaft 54 is connected with a' clutch element, indicated at 58, adapted upon inward axial movement of the shaft 54 to engage a companion clutch element, indicated at 51, which is operatively connected, in any suitable manner with the record wheels 49 for resetting said-wheels to zero reading. A spring, indicated at 58, may be positioned between the clutch element 56 and 51 for normally maintaining said elements out of engagement with each other so that the shaft 54 and wing knob 55 will remain stationary during the normal operation of the register wheels 49.

In order that the counter 48 may be operated in predetermined relation with the axial movement of the quill 24 and spindle I5, I have mounted a small spur of the drive shaft 51 in fixed relation therewith. A spur gear 81 is secured on one end of the worm shaft 35 in the plane of the spur gear 80. The gears 80 and GI are operatively connected with each other by a clutch element which, in this instance, is an idle gear 82, which is rotatably mounted upon a pin or stud secured to the housing II by a boss 64 and screw 65, as shown in lf'igure 5. The idle gear 82' is slidably mounted upon the stud 83 so as to move from an operative position in meshing engagement with gears and OI to an inoperative position out of meshing engagement with said gears. In order that the idle gear 82 may be releasably maintained in either the operative or the inoperative position, I have provided the hub 88 of the gear with a spring pressed ball 81 which is adapted to travel in either of two annular grooves '8 formed in the peripheral surface of the stud 63 in axial spaced relation to each other. The hub 46 of they gear 62 may, as shown in Figures 2 and 5, be provided with an outward extending annular flange GI adjiwent the'outer end thereof toform a finger piece by which the gear may be manually moved axially into and out of engagement with the gears I and CL The relations of the gears 80 and I to each other and to the worm 34 and the worm the lead-screw 38, are such that each one-thousandths of an inch of axial movement of the quill 24- and therefore of the spindle IS and the tool carried by said spindle will produce one-tenth of a revolutlonof the counter drive shaft so that said measurement will be registered in counter 4!.-

The operation of the with the tool positioning mechanism comprising worm 44, gear 36, and lead-screw 33 will be now understood to be substantially as follows:

Assuming that it is desired to drill a hole in a piece of work, as W, mounted upon a table or support. as S of the machine arranged beneath the housing H. The drill or tool, as T, secured to the spindle II by the chuck 20 will be normally maintained in its uppermost position, as shown in Figures 1 and 3, for permitting the work W to be readily mounted on the support S. After the work has been mounted on the support the tool the clutch element gear 80 upon the outer end counter in connection may be moved downwardly by rotation of the I shaft 35 until the lower end of the tool contacts with the upper surface of the work, at which position of the tool the counter 46 will be set to zero by manipulation of the resetting shaft 54. This is accomplished by pressing the shaft inwardly against the action of the spring 58 to bring the clutch elements 56 and 51 into engagement with each other and then rotating said shaft by means of the finger knob 55 in one direction or the other until the counter is reset to zero. As the knob is rel ased'by the operator the spring 58 will return he shaft 54 to its outermost position, thereby disengaging the clutch element 58 from 81. It will now be observed that further downward axial movement of the spindle I5 and the drill '1 carried thereby will be accurately registered in the counter 46 and the operator may readily determine when he has produced a hole ofthe required depth by merely reading the counter.

When the hole oi the require depth has been formed the drill will be returned to its extreme uppermost inoperative position by the operator rotating the shaft 35 in the proper direction through the medium of the hand wheel 40. This traveled from the initial operative position and the zero setting of the counter owing to the register wheels being moved backwardly and the figures on said wheels appearing through the window in successive decreasing values. In other words the counter only registers the amount which will indicate the depth of the hole to be made by the drill or other work to be done by the tool mounted in the chuck 20 when such work is performed. It therefore follows that when the tool is moved downwardly into engagement with the work the operator may readily determine when the tool has moved a distance sumcient to perform its required function by reading the counter and without the necessity of calculation on'his part, as is often necessary with conventional tool positioning indicator devices such as a dial Although the construction and operation of the 5 device shown and described are particularly simple, practical and emcient, I do not wish to be limited to the exact details thereof, as itis evident that various changes maybe made therein without departing from the spirit of the invention as set forth in the appended claims.

I claim: r

1. In a machine of the class described having a rotatable tool supporting spindle mounted in a case for axial movement with respect to said case toward and from a work support, positioning mechanism including nected with said spindle and rotatably mounted insaid case; said shaft being extended outwardly at one end beyond said case and having handle means connected therewith whereby the shaft may be manually rotated, means for'indicating a shaft operatively conmitting motion from a wheel of one denomination to an adjacent wheel of another denomination and a rotatable drive shaft operatively connected with one of said register wheels, means operatively connecting the mechanical counter to the case in close proximity to the first mentioned shaft, and means operatively connecting the shaft of said positioning mechanism with the drive shaft of said counter for actuating said latter shaft in predetermined relation to said axial movement of the-spindle including a pair of gear members, one of said gear members being mounted on the shaft of the positioning mechanism intermediate the handle and said case, the other one of said pair of gears being fixedly secured to the drive shaft of the mechanical counter, and an idler gear rotatably connected with the case in meshing engagement with said pair of gear members.

2. A structure as in claim 1 wherein said idler gear is connected 'with the case for movement with respect thereto into and out of engagement with said gear members, and means connected with said idler gear for producing said movement thereof.

WIILIAM L. MACRAE. 

